1. Field of the Invention
The present invention relates to railway transport facilities, and more particularly, to a method of their speed control and to a device for effecting same.
2. Description of the Prior Art
To ensure optimal operation of a shunting yard (or a hump) it is necessary to be able to provide efficient control of the motion speed of said railway transport facilities (of wagons, open wagons, flat wagons, tank wagons etc.), as, for example, to decelerate, accelerate, stop or set in motion stationary transport vehicles.
Numerous methods and means known in the art are presently used to provide speed control of railway transport vehicles.
There is a well known method which is capable to provide deceleration of a railway transport vehicle by way of jamming its wheels between two beams accomodated along a rail, at both sides thereof.
In the described method, however, the actual speeds of transport vehicles, set in motion after being released from delay mechanisms, differ greatly. This phenomenon is due to the fact that the friction coefficient between the surfaces at the "wheel lateral faces/beam faces" is highly unstable because of lubricants, paint, sand, moisture, etc. getting onto said surfaces, as well as due to temperature changes and other factors. Moreover, this method cannot, in principle, be used for speeding up transport vehicles. Therefore, other methods and devices, to be used in shunting yards and to provide speed control (deceleration and acceleration) of transport vehicles, should be capable of employing force interaction present between one, at least, pressure element and a wheel of a transport vehicle, said interaction to be accomplished in the region of mechanical trajectory (motion path) of said wheel. (See, e.g. "Zheleznye Dorogi Mira" /World's Railways/ magazine, 1981, No. 9, pp. 17-18, 27.)
The essence of the above-mentioned method for speed control of railway transport facilities consists in that within the railway track section, chosen as a location for the above control to be effected, the lower flange regions of the outer wheel rim surfaces (being rear, as relative to the train set movement during acceleration, or front, in case of deceleration) are adapted to effect force action by their pressure elements (by rollers, rods, screw faces of conveyors), said elements being located on the way of wheel's motion, in other words, they should be placed ahead of a wheel or behind it. (See, for example, FRG Patent No. 1530302, Int. Cl..sup.3 B61 j3/06).
This method is advantageous in view of the fact that during its realization the force action produced by the pressure element is practically independent of the friction coefficient, and the value of said force effect can be precisely proportioned. This method is taken as a prototype.
It should be noted, however, that the force value acting on the wheel, in accordance with said method, has a strictly limited range which is dependent on the transport vehicle force component applied to the wheel concerned. If this range is exceeded, the result may be running of the wheel over the adjacent pressure element or derailment of the transport vehicle.
This happens to be an essential limitation of the above mentioned method since, for trouble-free operation of the system, the acting force value should correspond to the value of its vertical component. This vertical component should not exceed 17 kN, so as to include the possibility of interaction with "light axles" (i.e. with unloaded wagons) which sometimes makes it difficult, or even impossible, to deal with train sets composed of only a few (8 to 10) wagons.
A device, realizing the described method, is made as a carriage used for displacing railway wagons and other vehicles of rolling stock. Said device comprises two pairs of pressure rollers, capable of extending and retracting transversely to the railway line direction.
One of said pairs, while performing said extending or retracting motion, is disposed some distance ahead of the wheel, while the other is disposed the same distance behind the wheel, and both of them are found in the region of the wheel's motion path.
The pressure rollers can act upon the lower rear and upon the lower front part of the wheel flange, said area acted upon equalling one fourth of said flange. The device itself moves along additional rails laid parallel the existing railway lane and inside thereof, and said device being set in motion by a cable connected to a drive unit.
When a wagon, with its sheels between the extendable rollers, moves faster than said carriage does, the wheel flange starts pressing-down on the roller located ahead of the wheel. The potential energy accumulated by the wagon will become transmitted to the carriage via the roller, and further through the cable to the drive unit, which will absorb said energy. Accordingly, the wagon speed will be slowed down to that of the carriage.
If a wagon, with its wheels between the extendable rollers, moves slower than the carriage does, the pressure roller being located behind the wheel starts pressing down on the flange corresponding to the rear lower fourth of the wheel. In addition, the energy from the drive unit will be delivered to the wheel via the lower roller, carriage and cable, thus increasing the wagon speed to the level equalling the carriage speed.
The above-mentioned interaction between the pressure rollers and the wheel flange (both during deceleration and acceleration) is accompanied, however, with the emergence of a force component directed vertically upward. It is therefore required to impose a strict limitation on the force magnitude of such an interaction, since in cases when said vertical component exceeds the value of weight force applied to the corresponding wheel axle, one can expect separation of the wheel from the rail head with a possibility of subsequent derailment of the wagon. Thus, the possibility of raising the efficiency of such controlling actions is sufficiently diminished.